Projectile with a delayed explosion



July 2, 1968 R. B. YOUNG PROJECTILE WITH A DELAYED EXPLOSION 2Sheets-Sheet 1 Filed Nov. 29. 1966 4 2 w V Q o o owon 4 INVENTOR. 056273. You/VG July 2, 1968 R. B. YOUNG PROJECTILE WITH A DELAYED EXPLOSIONFiled Nov. 29, 1966 2 Sheets-Sheet 2 z s I /////////////////////////Q lw 0000 0 0 2 0 0 0 0 0 0 0 0 000 4 a 00 0 0 0 0 0 0 0 0 0 0 0 4 l MQWOQOOOO .040 OO QQOQ I I I 0. 0 1, ,1 l r 4 1 u .u H /7 ,L./ 1. a 7

INVENTOR. 12086367 5. Yo wva My my United States Patent 3,390,535Patented July 2, 1968 ice 3,390,635 PROJECTILE WITH A DELAYED EXPLOSIONRobert B. Young, Greenbelt, Md., assignor to the United States ofAmerica as represented by the Secretary of the Air Force Filed Nov. 29,1966, Ser. No. 597,821 3 Claims. (Cl. 102-4) ABSTRACT OF THE DISCLOSUREA projectile is disclosed in which the explosion is delayed in animproved predetermined manner. The projectile is fired from a casingwhich contains the projectile and a propellant. The projectile is formedwith a central hole or core for tightly receiving a burst tube. The endsof the latter are closed except for an opening which slidably receivesone end of a centrally located rod. The other end of the rod is anchoredin the casing. The tube contains an explosive charge. The length of therod is predetermined to give the required time delay in exploding theprojectile by uncovering the opening in the tube as the projectile movesalong the casing, thus allowing the gases from the propellant to reachthe explosive charge in the tube to cause an explosion of theprojectile.

When launching a missile from an aircraft it is necessary that themissile or projectile be exploded, not only at a designated point inspace in order to hit the target, but also at a minimum safe distancefrom the point of delivery of the missile. Strict control of the time ofexplosion after delivery therefore is imperative. This requirement isdifiicult to attain, especially in the case of close targets on accountof extreme shortness of time that might be available between theignition of the full propellent charge and the explosion of the missile.Moreover, even in the case of distant targets, fuzes of the cord type,when used to ignite the propellant of a missile, are not altogetherpredictable as to rate of burn. Some control might be exercised byregulating the character and quantity of the propellant but thisexpedient is not sufiiciently critical and definite in pinpointing wherethe explosion will take place.

Other forms of controlled initiation of the igniting devices have beenproposed, such as the pyrotechnic delay fuzes operated by a hot wire,also the mechanical escapement form of fuzes which rely on the amount ofacceleration of the projectile. However, these fuzes are complicatedfrom the mechanical standpoint, and are quite expensive. Some of themare overly sensitive to high acceleration and very few, if any, give thehigh degree of control of the time and place of the explosion that isnecessary, particularly when using a projectile which propagates theignition through the propellant at a fast rate and the target is close.

An object of the invention is to provide an improved fuzing means forigniting the propellant and exploding a projectile propelled or droppedfrom aircraft.

Another object is to provide a grenade fuze of inexpensive characterwhich can be adjusted to give any regulated amount of delay between thecomplete ignition of the propellant and the bursting of the projectile.

These objects are attained in brief by providing a central bursting tubewithin the projectile and timing the bursting period by permitting theheated propellent gases to enter and explode the tube at a predeterminedtime after the propellant has been ignited.

While the invention has application to the propelling of a missile orprojectile out of a gun, I have shown, as a typical use, the operationof the improved fuzing structure in connection with aircraft delivery ofthe projectile.

The invention will be better understood when reference is made to thefollowing description and the accompanying drawings.

FIG. 1 represents a longitudinal sectional view of a missile includingthe improved explosion-delay-feature constituting the subject of thepresent invention;

FIG. 2 is an end view of the missile looking upwardly from about theposition of the line 2-2 in FIG. 1; and

FIG. 3 shows the relative position of the parts of the improved grenadefuze just prior to the explosion of the projectile.

Referring to FIG. 1, reference character 1 represents a cylindricalcasing of iron, open at the lower end and provided at its upper end witha heavy transverse wall 2 which has a central threaded opening. Thelatter merges into an extended opening 4, passing through the entirethickness of the wall.

A grenade fuze 5, shown in outline, and may be of any suitable andwell-known type, is secured to the upper flat surface of the wall 2. Thelower end of the grenade fuze is provided with a threaded extension 6which engages the threads of the central opening. This extension ishollow and has a depending rod 7, also hollow, extending through theopening 4. The interior of the threaded extension and the rod 7 are incommunication with the charge in the interior of the grenade fuze. Thelatter has the usual safety pin 8, a spring-operated lever, a strikingpin and primer, also an igniting charge, all of which are known in theart and therefore need not be described.

When the charge is ignited in the manner explained hereinafter, theheated products of combustion from the grenade fuze are forceddownwardly through the passageway into the compartment 9 from within thecasing and positioned directly below. The compartment contains arelatively long and stitf fuze rod 10, preferably made of a refractorymetal, which extends along the central axis of the compartment. This rodis anchored at one end in the wall 2 and for this purpose may terminatein a branched portion 11, the legs of which enter the metal of the wall.Thus the rod cannot obstruct the end of the passageway. The purpose ofthe rod will be described presently.

Surrounding the rod 10 and positioned somewhat remote from the wall 2,there is a tube 12 of relatively thin steel, threaded for a shortdistance at each end. A metal plug 13 is threaded into the tube at theends thereof, this plug having a countersunk central portion 14 and anaperture in the center (not shown) to provide a sliding fit for the rod10. A Teflon plug (not shown) having a press fit hole may be employed inthe countersunk portion to accommodate the fuze rod. The plug preventsthe entrance of gas, either hot or cold, yet allowing forced movement ofthe rod lengthwise of the tube. The latter is surrounded by a projectile15 which has a central opening that snugly receives the tube 12. Theprojectile has an outside diameter slightly less than the interiordiameter of the casing 1 so as to minimize friction as it moves throughthe casing. As indicated, the rod 10 may extend any desired distancebeyond the lower end of the tube 12 since it is supported at two pointsalong the central axis by the tube 12, which in turn, is snuglycontained within the projectile 15. The latter may be of any suitabletype which can be exploded by an internal blast.

The compartment 9 is filled with a propellant of any suitable andwell-known type before the projectile is introduced into the casing. Thetube 12 is also filled with an explosive charge by unscrewing one of theend plugs.

While various ways may be employed to place the bomb structure into ahorizontal or vertical trajectory the most effective manner would be todrop the structure from a plane over the target area. .t relayed-openingparachute could advantageously be connected to the satety pin 8. Thelatter would remain in place as tong as the parachute remainsundeployed; but when the :arachute opens at the set altitude. theresulting tug on the shroud lines would cause the pin to be withdrawn.lhis eriect is diagrammatically shown in FIG. 3 ln which the carachuteis designated 17. The latter need be reiativelv small since its functionis only to pull the D11] and not to sun port the bomb. The propellant inthe grenade :uze will have been caused to ignite and produce highlyheated gas which flows downwardly into the compartment 9 so as to setoff the propellant charge.

The resulting gas from the propellant will move the projectile 15 andthe contained tube 12 with respect to the casing. Tube 12 will thereforeslide along the .ixed fuze rod 10. Eventually the tube will have reacheda position such that the upper end of the tube will have cleared thelower end of the rod 10.

Inasmuch as the fuzing rod 10 will now have completely withdrawn iromthe central tube ts cated in FIG. 3, heated gases indicated at 16 pannow readily flow through the upper and opening in he tube to ignite theexplosive material therein. The result is that the tube 12 is caused toburst and this will immediately explode the projectile 15.

It is apparent that the time taken for the expanding propellent gases toreach the interior of the burst tube 12 through its end opening willdepend upon the time taken for the remote end of the t'uzing rod toclear the opening as the projectile and tube move together throu h theeasing. Thus, the length of the rod becomes a ready means forcontrolling the delay of any calculated amount oetween the time that thet'uze in the grenade [S lLl'llICd until the projectile is exploded.

The rod 10 may have any length desired. long or short. since it is wellsupported within the burst tube 12 either by the plugs 13 and/or by thesurrounding explosive material and the tube is in turn tirmly supportedwithin the projectile.

seen tnditill it is evident that the use of the improved fuziug rod andsurrounding tube as an explosion relay device can be .tsed with un-tiredprojectiles to advantage on account tr the extreme accuracy with whichthe length of the fuze rod and the resulting time delay can becalculated and tluplicated.

While .1 s ecific embodiment has been described, it is vtbvious thatnumerous changes may be made without departing from the generalprinciples and scope of the invention.

l in apparatus for exploding a projectile, the combilltlllOl'l of .1casing closed at one end and loosely surunding the pro ectile, apropellant between the closed end or the casing and the adjacent end ofthe projectile, a and extending rectilinearly through the casing andsetured at one end to the closed end of the casing, said trojectilehaving a central opening, a tube tightly fitted ithin the opening, plugmeans closing the ends of said tube. each or said plug means having anopening which ttidably receives the free end of said rod whereby the andextends through said tube, and an explosive charge tetween the rod andthe tube.

ll. The combination as set forth in claim 1 and in which said rod is ofsuch length that when the projectile is ttoved through the casing bysaid propellant, the open- .ltg in the tube is uncovered to permit theexplosive t arge tn the tube to be ignited by the propellent gases,thereby to explode the projectile.

The combination as set forth in claim 2, and in t ich said rod issubstantially of the same length as the tlhgth or the casing.

tlilefereuces Cited lWITED STATES PATENTS ...llll39,l34 F1917 Steell0219.2

TAMUEL W. ENGLE, Primary Examiner.

